Cascading Drop Downs - Method Error 500

Hi, I have some cascading dropdowns which work great when previewing the page locally through VS.

But when I upload my files to my web host and preview the page I get an error message Method Error 500 on each of the dropdown boxes.

As well as my own pages I have taken from the web the example I used, and I still get the same error. The example that I used is here - http://www.mikeborozdin.com/post/creating-linked-drop-down-lists-with-the-cascadingdropdown-control.aspx

On reviewing the error through Fiddler the errors show:

Unknown web method GetContinents

Unknown web method GetCountries

Unknown web method GetTerritories

Unknown web method GetCities

Thanks for any advice I've been stuck on this for days...